Propulsion device



June 3, 1947. P. F. HACKETHAL 2,421,692

PRoPULsIo'N DEVICE Filed July 20, 1942 2 sheets-Sheet 1 xwk June 3,1947.

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2 Sheets-Sheet 2 Patented June 3, 1947 4 2,421,692.' N PROPULSION DEVICEPaul F. Hackethal, Cockeysville, Md., assigner to Everel PropellerCorporatiomaltimore;Md., a

corporation of Maryland Application July` 20, 194a`serial No. 451,601`

propeller must either be of abnormal size or the number of its bladesmust be increased, either of which changes results in distinctdisadvantages. Among these are, iirst, increase in landing gear sizeandweight to accommodate the larger diameter propellers; second,increase in tip speed and torque with its increase in addedcounteracting drag on theairplane, and consequent reduction in airplanespeed; third, decreasing the amount of the pilots or gunners vision; andfourth, lowering of the propulsion eiliciency of the propeller byincreasing the number of its blades. y Y 'l The contra-rotatingpropeller overcomes these disadvantages by providing a small propulsionunit of high efficiency driven from a single engine. engine isnotutilized without means for varying the pitch angle of the blades. i

Attempts have been made to vary the pitc of contra-propellers both bypilot control and automatic governor control, but the very nature ofthepropeller construction presents engineering diiculties which haveprecluded an eicient pitch changing device and has retarded Vthedevelopment and use of the otherwise eilicient pro- Deller.

Itis therefore the principal object of this invention to 'overcome thedifliculties heretofore encountered in varying the pitch ofcontra-rotating propellers.

Another object of this invention is to provide a contra-rotatingpropeller in which the blades are so mounted that they automaticallyassume the most effective pitch angle under different night conditionsto utilize the full horsepower of the engine.

A further object is to provide a propeller construction comprisingtandem propellers rotating in opposite directions in which the blades ofeach propeller automatically assume the most efcient operating pitchindependently ofthe other.

Yet another object is to provide a means for But here too, the fullefficiency ofthe `changing the pitch of dual propellers of a ccntra- 4rotating propulsion unit for aircraft in which there is nointerconnection between the dual Dropellers or between the propellersand other parts r of the aircraft. I

A still further object isto provide means for automatically varying thepitch of contra-rotating propellers, the" construction of which providesfora minimum of moving parts, a minimum of weightand a minimum of careand inspection fora maximum of operating eciency, s

Briefly stated, my invention comprises freely pivotally mounting theblades in each of the dual hubs of a contra-rotating propeller withtheir gravity axes inclined to their pivoting axes whereby centrifugaland aerodynamic forces acting on the blades move the blades through the`arc of a cone until the forces are in equilibrium, at which time theblades automatically assume theniost` eifcient pitchangle for the nightcondition encountered. The principles `underlying such a method ofautomatic pitch change are thoroughly disclosed in my copendingapplication, s

Serial N0. 392,966, led May 19, 1941 (Patent No. 2,359,265,VOfrSeptembeI' 26, 1944), and it is not thought necessary to discussthem further in this specification.

In the accompanying drawings which illus-r broken away, in actualitythey extend into a gear box (not shown) from which they are impartedrotational motion in opposite directions.

It will be noted that the inner shaft I extends beyond the, outer shaft2 and is stepped to provide shoulders 3` and 4 and is also externallythreaded as at 5 near its outer end.

A forward hub 6 is splined to the outward extension of the shaft lasindicated at 'l and'is concentrically ailxed thereto by means of a rearannular wedge 8 seated against the shoulder 4 and .fitting within atapered extremity 9 of the I axial bore I0 of the hub and alforwardannular wedge II fitting, within asecond taper I2 of the bore I0. Acylindrical nut I3 is threaded onto the screw threaded `portion '5 ofthe shaft I and engages the wedge II to move it toward the wedge l8 tosecure the hub IB to its shaft. A locking device I4 is provided toprevent loosening of the nut I3 after adjustment.

A rear hub indicated generally as I5 is similarly mounted on the shaft 2by means of splines I6, annular wedges I'I and Island afdraw-up.. nutI9. A locking .ring 20 circ'iizmferentially serrated both externally andinternally to en gage serrations in the hubs bore and on the nut I9serves to prevent rotation of the nut after ad# justment. The lockingring is heldA against longitudinal displacement by means of asnap ring2| fitted into th'e looregof.A the-nubi Iifand a spigot 22 formed on oneendof a flanged" colL lar 23 which is aixed to the forward face of thehub I5 by means of cap screwslZl The opposite end of the collar 23hassecured thereto an annular plate 24 the inner circumference 25 ofwhich provides a bearing surface for engagement with a bearing ring'-'2'63 fitted' around the shaft I-against the shoulderfSi'to maintainaxial alignment of the outer ends-tof the two shafts. l

As, above set forth, the propeller--blade'sharel mounted' in the hubsfor freepivotal'movement about'the iarc -of'aI cone. To accomplish this,reach of thehubs 6i and I5iare radially liorecltofpro'-i vide` steppedksockets internally screwI thread-1 ed` asV at 3l. such sockets foreach-hub; obviously more or less mayv loe-provided,` depending upon'thefn'iimber of blades employed;-

Adapted vto be mountedwithin eaclr of the-sockeets 3U is avblademounting sleeve 32 tof* circular cross section which isprovided"withia-borei33 machined at an angle to the longitudinal-[axisof thesleeve. 'Ih'eV inner end ofi the'bore133 isv providedwithginternal screw threads 34f 'andy is-` also'inter-nallyflangedffas'at 35 'I'lie'outerfporithe socket30, is turnedfdownAconcentricallyl with-` the bore 33 to formi ,a-skirt-S whichis'lp'roevidedfwith al series of spacedA radial slots 31'; 'the' purposeof which will'be describedateri- Near the inner end-of thesleeve 3'2 isanexa ternal peripheral flange 38 againsttthe'outerface'- ofV whichfisfitted the 'inner race v39`-of a' combined radial andthrustanti-frictional bearing?4'I"I".` The outer race'4I of thebearingi'lllllts iiritliirnan` internally flanged cylindrical 1 mit '42kjagain'st--tlie`v tain the above :construction inassembly; vvhileausuitableY oil' packingring- 45"-4 is Ypositioned beitween the nut andsleeveto Vmaintain properJ sleeves 32 within their sockets' 30,' thenut-*42jisf screwed into'y the threaded portion: 3I until the bearingV4S isU forced into the stepped-portion 41 of theisocket wheretit-forms-with" the bearing 4'Ila cantilever supportwhichiperfnits"anti-fricI-,ional pivotal movement' offthe'sleeve within the socket;J i

While -for the purpose -of simplicity they have not been illustrated;-suitable ,pitch change 1iiniti devices, such asA havebeen shownz arid'Adescribed:

in another copending applicationof' mine, Serial No; 445,621; filed'June- 3; 1942,* may bejincorevv porated in the hubs-'to'serveas stopsfor-*highL andlow pitch-positions of the-sleeves' Theshanks-bfthepropellerfblades 5I- are externally-threaded as atv ztoengagethe threads`vr 4 34 of the sleeve bores 33 when they are tted therein as shown inthe drawings. After the blades have been screwed into their sleeves andtheir initial pitch has been adjusted they are fixed against furthermovement by clamp members 53 secured around the slotted skirt portion 36of4 th'e sleeves. These `clamp members.53 may also seri/eas'counterweight's, .as-1 illustrated in Figure '1, functioning to modifythe mass distribution of the blades.

While, as heretofore stated, the centrifugal and aerodynamic lforcesacting `on the blades yautomatically cause them to assume the mosteilicientfpitcn 'angle for given operating condition's-,-itlisadvantageous that there be a synchronizedmovement of the blades in eachpropeller. To accomplishfthifsa series of bevel pinions 55 are `mounted.to rotate on radial pins 56 secured in the hub and positioned in theplane of the blade sleeves 32 and angularly equidistanttherebetwi'een.-L These pi-iiins 'areW adapted' to'A mesh with bevelfgear segmentsY 5T whicl-are'fseciired'- to thef'inner faces 'of' thebl'ade'sleeves 3`2-l In' operation thedual, tandeml propellers rotatedin opposite directionsandlatsynchr speedbytheir common source of`power lthus rotated;` the'several'blades of ""e'achjpr are" subjectedv` tovkboth` centrifug'ai and aerodynamic forces acting thereon; The lilla-desibeingpi'vctally mounted in their respective nulos-asile scrib'edabovearer affected-j.v These forces effeti'affchange in= the pitch" of* theplanes' depending on the' spee'dmof "the-` engine Vand cbnditions'of'iligli-t Whentnesefferces a'reiii equilibrium the bjladesf endif desire`to-loeflimited tnereiiionly by the state of the prior art and-*the'scope' of the-appended claims.

Ifclaim-z- 1: A- propulsion device -fer aircraft-comprising apair-oftandem' hubs rotatable in oppositezd'r'c-i tionsabout a common axis,arplu'rali'ty ofifadial sockets inA eeen hub; a' sleeve mountedin*eaeii` v socket` andy adaptedf'r free pivotalmovement about theaxisthereof, ,a bore in each sleevegtle" axis of" said bore deniiigjan anglewitli'andin: tersectingthe axis ortne'soeket; a piopelleriade" securedin' eachi'boie, andacpliiralityfof ync'liro'l nizing meansdisposedcircumferentially` ain" trie' "propelleriand"interconnectingithe bladesof eachA individual propeller' te mamtairitnef pitch a pair of tandemhubs rotatable in oppositediree: tions about'fa fcomiiioii axis; a-`pluralityo radial defining an angie with and intersecting the axis ofthe socket, a propeller blade secured in each bore, clamping meansfor'securing the extended sleeve to the propeller blade, said meansbeing weighted and serving to assist the blades in assuming variouspitch positions in response to Variations in iiight conditions, andsynchronizing means disposed circumferentially around the propeller andpivotally mounted in the piane of the blades and associated therewithfor maintaining the pitch of the blades of that propeller uniform forall pitch Variations.

PAUL F. HACKETHAL.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,455,442 Leparmentier May 15,1923 2,234,196 Prewitt Mar. 11, 1941 Number Number 6 Name Date Tidd Oct.6, 1942 Wingier Dec. 19, 1933 Everts July 29, 1941 Hubbell Dec. 10',1935 Gathmann Apr. 1, 1941 Wilson Feb. 13, 1934 McCauley June 3, 1930Squires June 13, 1933 Seppeler Mar. 29, 1932 Waseige Apr. 7, 1941 HavillJuly 23, 1935 Fraser Oct. 29, 1940 Hackethal Sept. 26, 1944 ReissnerMar. 3, 1942 FOREIGN PATENTS Country Date Italy Feb. 14, 1935 GreatBritain Dec. 5, 1938 Great Britain June 30, 1939

